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Tie  natural  Ttoloiy  of  a  Doctrine  of  tie  Forces. 


By  Prop.  BENJ.  N.  MARTIN,  D.  D.,  L.  H.  D., 


University  of   the   City  of  New  York. 


fuom  the  plloceedings  ob"  the  university  convocation  held  at  albany,  n.  y 
August  1st,  2d  and  3d,  1871. 


THR 

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Received  187 


Natural  Theology  of  the  Doctrine  of  the  Forces.     701 

t 

\.    Of  c 
THE  NATURAL  THEOLOGY  OF  THE  DOCTRlte  0£Jfli] 


By  Prof.  Benjamin  K  Martin,  D.  D.,  L.  H.  D., 

University  of  the  City  of  New  York. 


The  great  change  which  has  passed  over  the  philosophy  of  physics 
in  our  day,  re]ates  to  the  doctrine  of  the  forces;  and  scientific  teach- 
ing now  affirms  the  correlation,  or  convertibility,  of  them.  all. 

The  idea  of  force,  which  lies  at  the  basis  of  this  view,  is  yet  far  from 
being  clearly  defined  in  the  conception  of  the  physical  philosopher. 
It  is  vaguely  conceived  as  something  lying  back  of  phenomena,  to 
which  the  latter  are  to  be  referred  as  their  ground  or  cause.  All 
the  varied  phenomena  oij  the  physical  world,  and,  indeed,  of  the 
physical  universe,  are  attributed,  not  as  recently  they  were,  to 
imponderable  fluids  or  agents,  but  to  motions  of  the  masses,  or  ihe 
particles,  of  matter  ;  motions  which  are  themselves  due  to  the  action 
of  certain  impelling  forces.  The  chief  interest  which  attaches  Lo 
the  subject  arises  from  the  apparently  successful  attempts  that  have 
been  made  to  convert  one  of  these  forces  into  another,  and  thus  to 
arrive  at  a  generalization  which  will  admit  of  our  grouping  them 
together,  as  forms  or  manifestations  of  a  single  force. 

The  great  physical  agencies  of  our  world,  light,  heat,  electricity, 
and  the  chemical  force  (known  now  as  chemism),  are  so  unlike  in 
their  ordinary  aspects,  that,  during  all  the  earlier  stages  of  our 
inductive  progress,  not  only  was  their  nature  unknown,  but  their 
unity,  their  common  character,  was  unsuspected.  Light  was  regarded 
as  a  peculiar  emanation  from  a  certain  class  of  bodies  called  lumi- 
nous ;  heat  was  a  kind  of  fluid  filling  the  pores  of  bodies,  and  capa- 
ble of  being  squeezed  out  of  them  by  compression,  as  water  from  a 
sponge  ;  of  electricity,  it  was  long  disputed  whether  it  consisted  of 
one  fluid,  manifesting  its  presence  by  excess  and  defect,  or  of  two 
fluids  of  opposite  character,  which  give  respectively  the  vitreous  and 
the  resinous  electricities  ;  magnetism  was  conceived  to  be  due  to  a 
fluid  acting  from  one  pole  of  a  magnet  to  another,  in  curved  lines ; 
galvanism  was  deemed  to  be  a  fluid  closely  related  to  the  nervous  fluid 
of  the  human  system  ;   and  in  addition  to  all  these  we  had  the  force  of 

239 


702  University  Convocation. 

chemical  affinity,  governing,  in  a  manner  that  was  deemed  entirely 
peculiar,  the  chemical  reactions.  It  was  long  before  any  common 
ground  in  all  these  apparently  diverse  agencies  was  even  suspected  ; 
but  within  a  recent  period  a  change  has  passed  over  these  modes  of 
conceiving  of  the  imponderable  agents  of  our  general  chemistry. 

It  began  to  be  understood  that  light  was  not  a  distinct  substance 
sent  forth  in  radiating  lines,  but  a  vibration  or  regulated  motion,  in  a 
universally  diffused  medium  of  the  rarest  kind,  a  motion  analogous  to 
that  vibration  of  the  air  which  reports  itself  to  the  ear  as  sound.  By 
this  discovery,  one  of  the  great  supports  was  stricken  from  an 
erroneous  mode  of  conceiving. 

Early  in  the  present  century,  however,  the  mutual  relations  of 
some  of  these  agencies  began  to  be  more  clearly  perceived.  Galvani's 
original  discovery,  made  in  1790,  that  a  movement  can  be  excited 
in  the  limbs  of  an  animal  by  the  application  of  two  metals  to  the 
nerve  and  the  muscle,  was  made  in  connection  with  the  conductor  of 
an  electrical  machine;  and  was  originally  announced  as  a  kind  of 
animal  electricity  ;  and  this  connection,  iCat  first  rather  conjectured 
than  proved,  succeeding  researches  confirmed."*  Ten  years  after,  in 
1800,  Yolta  contrived — by  means  of  the  instrument  which  was 
named,  from  its  inventor,  the  voltaic  pile — to  accumulate  this  force 
so  as  to  bring  it  much  more  fully  within  the  sphere  of  observation. 
The  general  attention  of  observers  was  thus  fixed  upon  the  very 
interesting  phenomena  of  voltaic  electricity,  and  many  wonderful 
properties  and  beautiful  laws  were  brought  to  light.  The  discovery 
in  1820,  by  Oersted,  of  Copenhagen,  that  the  conducting  wire  of  a 
voltaic  circuit  affects  the  magnetic  needle,  brought  prominently  for- 
ward the  idea  of  the  connection  of  these  forces;  and  the  term  electro- 
magnetic marks  the  step  which  identified  the  two  as  really  forms  of 
one,  so  that  electricity,  magnetism,  and  galvanism,  became  insepara- 
bly connected  in  scientific  thought  as  manifestations  of  a  single 
agency. 

Contemporaneous  with  this,  was  the  brilliant  epoch  of  Davy  and 
Faraday.  It  had  been  found  that  under  the  influence  of  the  voltaic 
circuit  certain  compound  substances  are  decomposed.  Water,  for 
instance,  was  resolved  into  its  elementary  gases ;  and  some  metallic 
salts  suffered  a  like  resolution  into  their  constituent  elements.  Davy 
felt  assured  that  not  only  these,  but  the  whole  body  of  the  voltaic 
phenomena,  are  chemical  in  their  nature;  and  in  1806  he  uttered 

*  Wheneirs  Hist,  of  the  Inductive  Sciences. 

240 


Natural  Theology  of  the  Doctrine  of  the  Forces.     703 

his  thought,  more  as  a  conjecture  than  a  discovery,  "  that  chemical 
and  electrical  attractions  were  produced  by  the  same  cause,  acting 
in  the  one  case  on  particles,  and  in  the  other  on  masses."* 

This  anticipation  of  Davy's  was  taken  up  by  his  successor, 
Faraday,  who  proved  that  the  electric  current  in  a  voltaic  pile  is 
due  to  "  the  mutual  chemical  action  of  its  elements."  He  intro- 
duced a  distinctness  of  conception,  and  an  accuracy  of  expression, 
which  contributed  greatly  to  the  elucidation  of  the  subject.  He 
showed  that  the  wire  of  a  voltaic  circuit  "  conducts  chemical 
affinity,"  and  that  "electricity  is  only  another  mode  of  the  exertion 
of  chemical  forces."f  By  his  researches,  principally,  the  identity  of 
chemism  with  the  various  forms  of  electricity,  was  established ;  and 
we  have,  as  the  great  result  of  Faraday's  labors,  the  science  of 
electro-chemistry. 

Meanwhile,  in  other  departments,  a  similar  progress  was  going 
on.  Not  only  was  the  theory  of  light  reduced  to  the  simple  con- 
ception of  the  regular  and  rapid  movement  of  particles  of  a  rare 
medium,  but  the  conception  of  heat  underwent  an  analogous  change. 
It  was  found  that  the  conception  of  a  physical  substance  termed 
caloric,  which  had  served,  during  all  the  last  century,  to  explain  and 
classify  many  of  the  phenomenar  afforded  only  an  imperfect  and 
unsatisfactory  account  of  them ;  and  the  attention  of  observers  was 
directed  to  the  subject  in  the  hope  of  gaining  some  clearer  ideas. 
Among  the  earliest  of  these  investigators  was  our  distinguished 
countryman,  Count  Rumford.  A  paper  read  by  him  before  the 
Royal  Society,  in  1798,  gave  account  of  a  very  remarkable  and 
happy  experiment,  which  elucidated  the  nature  of  heat,  so  far  as  to 
show  that  it  could  not  be  a  distinct  substance.  He  had  been  struck 
by  the  very  great  amount  of  heat  generated  by  the  mechanical 
process  of  boring  cannon ;  and  that  process  gave  him  the  idea  for 
his  experiment.  He  took  a  thick  metallic  cylinder,  and  immersing 
it  in  water  at  a  temperature  of  60°,  applied  to  it  a  metallic  plunger, 
which  was  firmly  pressed  against  the  end  of  it,  while  the  cylinder 
itself  was  steadily  turned  by  horse-power.  At  the  end  of  an  hour, 
the  temperature  of  the  water  had  risen  to  107° ;  in  thirty  minutes 
more  it  reached  140° ;  at  the  end  of  two  hours  the  mercury  stood 
at  178° ;  at  two  hours  and  twenty  minutes  it  was  200°;  and  at  two 
hours  and  thirty  minutes  the  water,  which  amounted  to  two  and  a 
half  gallons,  actually  boiled.     "  It  would  be  difficult,"  he  says,  "  to 

*Whenell's  Hist,  of  the  Inductive  Sciences.  fib. 

241 


704  University  Convocation. 

describe  the  surprise  and  astonishment  expressed  in  the  countenances 
of  the  bystanders  on  seeing  so  large  a  quantity  of  water  heated,  and 
actually  made  to  boil,  without  any  fire."* 

This  experiment  ought  to  have  been  decisive  against  the  theory 
of  the  material  nature  of  heat,  but,  for  a  long  time,  it  failed  to 
attract  the  attention  which  it  deserved ;  and  only  recently,  by  the 
confirmatory  experiments  of  Joule,  in  England,  did  it  reach  the 
rank  to  which  it  was  entitled.  It  shows  us  that  heat — a  thing 
which  can  be  supplied  inexhaustibly  by  the  simple  friction  of  a 
borer — is  not  any  material  substance,  however  attenuated,  but  must 
be  conceived  as  a  peculiar  mechanical  condition  of  the  particles  of 
matter.  This  general  view  I  need  not  dwell  upon.  It  has  been 
illustrated  with  so  much  ability  and  interest  by  Tyndall,  in  his 
Lectures  on  Heat,  that  it  suffices  to  refer  to  his  book  for  the  complete 
elucidation  of  the  subject.  Heat  is  now  understood  to  be  a  rapid 
motion  of  the  particles  of  any  substance — of  what  nature  we  do 
not  yet  accurately  know — but  this,  unquestionably.  In  heating  a 
substance,  we  do  but  put  its  particles  into  a  state  of  rapid,  perhaps 
vibratory,  motion ;  an  elevation  of  temperature  means  an  increase 
of  this  movement,  either  in  rapidity  or  in  extent,  or  in  both ;  and  a 
lowering  of  temperature  means  a.  diminution  of  the  amount  of  this 
motion. 

Now  this  internal  motion  of  the  particles  of  any  body,  is  found 
to  sustain  a  relation  to  the  mechanical  motion  of  the  mass  as  a 
whole ;  and  the  one  of  these  motions  is  convertible  into  the  other. 
When  a  ball  is  dropped  from  a  height  upon  a  solid  body,  and  its 
motion  suddenly  arrested,  the  ball  becomes  heated  ;  that  is,  the 
mechanical  motion  of  the  mass,  its  transfer  by  a  molar  force  from 
place  to  place,  is  changed  into  a  motion  of  the  particles  among  them- 
selves. These  are  thrown  into  rapid  vibration,  we  will  call  it,  for 
want  of  a  more  accurate  name  ;  that  is,  the  temperature  of  the  body- 
is  raised.  If  we  hammer  a  piece  of  iron,  it  becomes  hot ;  the  arrested 
mechanical  motion  of  the  hammer,  becomes  transformed  into  a  rapid 
agitation  of  the  molecules  of  the  mass  which  arrests  it. 

Heat  sustains,  moreover,  a  relation  to  light.  That  they  are 
closely  connected,  our  commonest  experience  teaches  us  all ;  but  how 
closely,  the  world  has  only  in  late  years  learned.  Light,  too,  is  but  a 
vibration  as  it  comes  to  us  through  the  transparent  ether  which,  as  a 
medium,  connects  our  world  with  the  stars  ;  and  hence  it  is  easy  to 

*  Tyndall ;  Lectures  on  Heat. 

242 


JVa tura l  Theol ogt  of  the  D o ctrine  o f  the  For ces.    7 05 

conceive  them  as  analogous  states  of  matter.  The  vibrations  of 
heat  have  only  to  be  sufficiently  increased,  and  the  heated  body  begins 
to  report  itself  to  our  eyes  as  a  luminous  one.  The  lower  tempera- 
tures are  dull  and  faint  in  their  gleam,  but  as  the  temperature  rises, 
that  is,  as  the  rapidity  of  the  motion  increases,  the  light  grows  more 
intense,  till  the  agitated  and  quivering  mass  glows  with  the  white 
light  which  represents  the  intensest  heat,  and  almost  forbids  our 
direct  vision. 

Light  also  stands  in  similar  relations  to  mechanical  force.  The 
sudden  arresting  of  a  mass  in  rapid  motion,  produces  not  only  heat 
but  light.  Tyndall  states  that  the  impact  of  one  of  the  solid  projec- 
tiles of  the  great  Armstrong  guns,  upon  a  target  at  Shoeburyness, 
sometimes  produced  not  only  heat,  but  a  flash  of  light  so  distinct  as 
to  be  visible  by  broad  daylight. 

JSTow  these  two  great  classes  of  agencies  to  which  I  have  referred, 
the  electro-chemical  force  on  the  one  hand,  and  that  of  light,  heat 
and  mechanical  force  on  the  other,  were  next  drawn  into  mutual 
relation.  It  was  found  that  not  only  would  the  voltaic  pile  develop 
heat,  as  in  many  arrangements  it  does  to  a  very  high  degree,  but  that 
certain  applications  of  heat  would  also  develop  the  phenomena  of 
electricity ;  and  soon  the  thermo-electric  pile  was  devised  as  by  far 
the  most  sensitive  instrument  for  the  measurement  of  heat.  Thermo- 
electricity has  now  become  a  very  important  branch  of  physics ;  and 
we  have  in  this  name  another  indication  of  the  general  progress  of 
the  identification  of  all  these  varied  agencies. 

The  exact  mechanical  equivalent  of  heat  has  been  determined  after 
a  vast  amount  of  careful  experiment  and  measurement,  by  Joule  in 
England,  and  by  Mayer  in  Germany  ;  so  that  it  now  seems  possible 
to  calculate,  on  the  one  hand,  the  amount  of  heat  which  would  be 
produced  by  the  arrested  motion  of  any  moving  mass,  and  on  the 
other  the  amount  of  matter  which  could,  be  put  in  motion  by  the 
extinction  of  a  given  amount  of  heat.  The  amount  of  force  required 
to  raise  a  weight  of  one  pound  through  a  height  of  one  foot,  called 
the  foot-pound,  is  the  unit. 

Thus  all  these  different  forces  are  found  to  be  but  varied  manifesta- 
tions of  the  same  great  agency.  They  are  different  kinds  of  motion, 
produced  by  a  force  which  is  not  many  and  diverse,  but  one  and 
simple.  The  varying  phenomena  are  identified  with  one  another 
through  their  common  relation  to  the  general  fact  of  motion,  of  the 
specific  kinds  of  which  we  have  yet  much  to  learn.     What  is  the 

243 


706  University  Convocation, 

particular  kind  of  motion  which  constitutes  heat,  and  how  it  differs 
from  that  of  light,  and  how  from  that  of  electricity,  we  do  not  know, 
nay,  are  perhaps  far  from  knowing ;  but  we  seem  pretty  well  assured 
that  these  different  kinds  of  movement  all  sustain  a  common  relation 
to  the  mechanical  motion  of  a  mass,  and  are  substantially  convertible 
into  one  another ;  and  this  is  what  is  now  meant  by  the  converti- 
bility, or  the  correlation,  of  the  forces  ;  they  are  all  interchangeable 
forms  of  a  single  force. 

I  pause  a  moment  in  view  of  a  generalization  so  interesting,  and 
so  comprehensive.  For  the  co-ordination  of  a  vast  number  of  remote 
and  apparently  unrelated  facts,  no  other  generalization  which  sci- 
ence has  reached  since  the  great  discovery  of  Newton,  seems  to  me 
so  remarkable.  The  varied  phenomena  of  nature  bad  been  already 
grouped  into  distinct  classes,  and  arranged  with  all  the  method  of  a 
scientific  order;  the  generalization  which  embraces  them  all,  is, 
therefore,  the  comprehension  of  a  whole  body — nay,  of  the  whole 
body  of  the  physical  sciences,  under  one  most  general  principle. 
The  explanation  which  this  generalization  affords  is  equally  happy. 
The  result  is  no  simple  registration  of  phenomena,  according  to  that 
superficial  view  of  induction  which  theoretically  denies  to  science 
anything  more  than  the  office  of  mere  observation.  More  true  to 
the  high  aims  of  the  intellect  itself  than  to  the  demands  of  that 
insufficient  theory  of  procedure  which  is  honored  under  the  name  of 
induction,  the  men  of  science  have  concurred  with  unwonted  unan- 
imity, first,  in  referring  the  phenomena  observed,  in  each  several 
department,  to  the  ground  which  alone  can  afford  a  satisfactory  view 
of  them  ;  and  then  in  embracing  all  these  distinct  branches  of  know- 
ledge under  what  we  may,  with  some  reservations,  call  a  universal 
expression.  The  consequence  is,  the  discovery  of  a  law,  on  the  one 
hand,  so  comprehensive  as  to  include  the  immense  and  varied  body 
of  natural  phenomena,  and,  on  the  other,  so  profound  as  to  furnish 
explanation  of  the  whole  vast  mass.  Each  phenomenon  is  an  intelligi- 
ble result  of  some  modified  operation  of  the  one  great  and  universal 
Force  of  Nature. 

It  is  a  point  of  great  interest  that,  in  this  wide  formula,  science 
seems  to  have  reached  the  extreme  limit  of  her  inquiries.  When 
these  specific  forces  have  once  been  thus  grouped  and  united,  no 
further  advance  in  generality  of  expression  is  possible.  The  problem 
has  been  reduced  to  its  very  simplest  form  of  statement.  These, 
navigators  on  the  great  sea  of  the  unknown,  set  out  by  different  and 

244 


Natural  Theology  of  the  Doctrine  of  the  Forces.     707 

even  opposite  courses ;  but,  sailing  thus  in  contrary  directions,  they 
•have  at  length  come  in  view  of  each  other ;  their  discoveries  have 
compassed  the  globe,  and  the  whole  orb  of  knowledge  stands  dis- 
closed in  all  the  simple  harmony  and  unity  of  truth. 

If  there  is  something  painful  in  the  idea  of  having  reached  the 
limit  of  research  in  so  great  a  sphere  of  inquiry — in  hearing,  as  it 
were,  the  last  word  of  science  in  regard  to  the  great  expansion  of 
her  thought,  we  may,  at  least,  feel  that  it  enables  us  the  better  to 
pursue  the  course  of  those  reasonings  upon  which  the  noblest  minds 
have  always  been  intent.  If  the  problem  is  solved,  we  may  the 
more  justly  inquire  for  the  bearing  of  the  solution  upon  the  great 
theme  of  our  present  inquiry. 

This  brings  us  to  the  question,  for  the  sake  of  which  I  have  entered 
into  this  account  of  the  doctrine  of  force,  as  at  present  held.  What 
is  to  be  the  bearing  of  this  great  discovery  upon  the  theistic  view  of 
the  universe  ?  What  is  to  become  of  our  conception  of  God,  when 
the  phenomena  of  nature  are  all  referred  to  general  or  universal 
laws,  and  these  are  affirmed  to  be  the  manifestations  of  one  compre- 
hensive, controlling,  and  universal  force,  operating  through  the 
unnumbered  ages  of  past  time  ?  Let  us  endeavor  to  trace  the  subject 
to  its  issues. 

Before,  however,  we  can  have  much  hope  of  gaining  any  idea  of 
the  bearing  of  this  discovery,  we  shall  need  to  inform  ourselves  some- 
what more  particularly  of  the  specific  character  of  the  force  thus 
indicated.  Under  what  form  of  thought  is  it  to  be  properly  con- 
ceived ;  or,  scientifically  speaking,  what  is  its  law  ? 

Here  it  is  first  to  be  observed,  that  the  general  expression  which 
we  have  obtained  is  not  absolutely  universal.  We  identify  several, 
perhaps  many,  of  the  forms  of  force  known  to  us,  but  we  have 
no  reason  from  that  fact  to  assume  that  we  have  thereby  identified 
them  all.  Each  of  the  forces  included  in  our  generalization 
has,  as  its  marked  characteristic,  a  definite  relation  to  physical 
motion  ;  we  may  find  reason  to  conclude  that  there  are  other  forces 
which  have  no  such  relation.  In  that  case  we  should  be  acting 
wholly  without  our  warrant,  if  we  should  insist  upon  stretching  our 
generalization  so  far  as  to  include  them.  There  is  a  group  of  force's 
which  together  govern  the  motions  of  atoms  in  space.  Physicists 
have  thus  far  recognized  no  others ;  but  I  can  hardly  be  wrong  in 
saying  that  the  force  by  which  an  atom  resists  the  compression 
which  would  crush  it  out  of  exitence,  is  one  of  a  wholly  different  order, 

245 


708  University  Convocation. 

and  has  no  relation  whatever  to  motion,  either  molecular  or  mechani- 
cal. Perhaps,  too,  other  forces,  relating  not  to  the  constitution  of 
matter,  but  to  the  operations  of  the  mind,  may  be  arrived  at,  which 
equally  refuse  to  come  within  the  generalization. 

In  speaking,  therefore,  of  the  convertibility  of  forces,  I  beg  that 
it  may  be  observed  that  I  speak  with  a  limitation,  and  refer  only  to 
the  motive  forms  of  force — to  those  general  and  diffused  agencies 
which  pervade  the  universe  and  give  movement  to  the  atoms  which 
compose  it. 

Of  these  forces,  then,  I  may  observe  that,  in  the  case  of  several 
of  them,  science  has  ascertained  the  existence  of  a  common  law 
which  affords  us  a  deeper  insight  than  we  gain  by  any  other  means, 
into  their  interior  nature.  The  great  law  which  governs,  and 
expresses,  the  diffused  operations  of  gravitation,  has  been  already 
determined  to  be  that  of  the  inverse  square.  Now,  it  is  quite 
remarkable  that  the  same  law  has  been  proved  to  be  the  one  which 
governs  the  attractions  of  electricity,  and  also,  on  independent 
grounds,  of  magnetism.  We  should  have  been  at  liberty  to  infer 
as  much  from  the  common  nature  of  these  forces,  but  it  so  happens 
that  the  proof  of  this  community  is  less  clear  in  the  case  of  gravita- 
tion than  in  that  of  some  of  the  others.  On  the  ground,  however, 
of  this  common  law,  we  may  feel  emboldened  to  identify  them  all, 
and  to  conceive  their  general  action  as  altogether  analogous  -to  the 
well  known  operations  of  this  familiar  agent. 

Let  us  suppose,  then,  the  universal  prevalence  of  such  a  force  as 
gravity  is  ascertained  to  be,  viz.,  one  that  corresponds  in  intensity 
to  the  mass  of  the  *  matter  involved,  and  which  varies  inversely  as 
the  square  of  the  distance.  That  gravity  exists  under  this  law  is, 
perhaps,  the  best  ascertained  of  all  physical  truths.  It  pervades  the 
universe  through  all  its  spaces,  and  it  reaches  and  governs  each 
minute  particle  of  matter.  Now,  we  shall  find  that  the  simple 
supposition  of  the  prevalence  of  such  a  force  will  give  us,  as  a 
result,  the  existence  of  the  other  phenomena — of  many  of  them,  at 
least — which  our  observation  has  recognized  as  other  forms  of  force. 
Gravity  is  abundantly  familiar  to  us  as  connecting  the  mass  of  the 
earth  itself  with  the  objects  upon  its  surface;  and  Newton  extended 
it  to  the  moon,  and  determined  first  her  motions,  and  then  the 
motions  of  the  celestial  bodies  generally,  to  be  governed  by  the  same 
force.  But  when  we  come  to  reason  about  the  force  which  governs 
the  relations  of  physical  objects  to  each  other,  we  fail  to  recognize 

246 


Natural  Theology  oi  the  Doctrine  of  the  Forces.    709 


it  with  any  similar  distinctness;  indeed,  we  have  failed  to  recognize 
it  at  all.  Yet  even  here  it  exists,  and  our  observation,  if  nice 
enough,  could  not  fail  to  distinguish  it. 

The  proceedings  of  the  Royal  Astronomical  Society  (vol.  xiv) 
contain  a  very  interesting  account  of  the  exact  methods  employed 
to  ascertain,  and  to  measure,  the  force  of  gravity  between  bodies  of 
moderate  size  on  the  surface  of  the  earth.  Dr.  Maskelyne  had 
previously  determined  the  fact  that  the  attraction  of  a  precipitous 
mountain  influences  the  direction  of  a  plummet  hanging  near  it, 
and  swerves  it  from  its  true  perpendicular  position  ;  but  more  precise 
and  extended  experiments  were  required,  for  the  production  of 
accurate  standard  measures  of  length,  which  had  been  determined 
upon  by  the  British  government ;  and  the  work  was  undertaken  by 
the  highest  scientific  skill.  A  cylinder  of  lead  was  cast,  with  the 
utmost  care  to  obtain  it  pure  and  make  it  uniformly  dense;  from 
this  were  turned,  with  exactest  nicety,  two  spheres  of  lead  of  some 
twelve  inches  diameter,  for  attracting-balls.  Then  two  small  balls 
were  added  with  delicate  torsion  suspenders,  the  motion  of  which 
was  to  be  accurately  observed.  But,  alas !  after  weeks  and  months 
of  observation,  only  the  most  irregular  and  inconsistent  results  were 
obtained.  It  was  found,  upon  inquiry  of  the  most  successful 
continental  observers,  that  the  slightest  changes  of  temperature 
between  the  bodies  were  sufficient  to  invalidate  the  results.  It  was 
necessary  to  deposit  the  apparatus  in  an  underground  apartment, 
so  as  to  obtain  as  nearly  as  possible,  an  absolute  uniformity  of  tem- 
perature, and  to  observe  it  by  means  of  a  telescope  through  a  glass  door, 
in  order  to  detect  the  slight  modifications  which  the  attraction 
exhibited.  Still,  with  such  minute  care,  aided  by  whatever  sug- 
gestions science  could  furnish,  observations  were  obtained  which 
authenticated,  and  measured,  the  force  of  gravity  as  an  actually 
existing  and  appreciable  thing,  which  exerts  an  agency  between  all 
the  masses  of  matter  on  the  surface  of  the  earth. 

Supposing,  then,  that  such  a  force  exists  and  operates  everywhere 
around  us,  let  us  endeavor  to  trace  it  to  its  results.  Recollect  that, 
by  the  very  supposition,  its  effect  must  be  faint  at  any  considerable 
distance,  save  when  the  masses  which  attract  each  other  are  very 
great ;  but  that  a  force  which  follows  this  law,  though  faint  at  con- 
siderable distances,  becomes  large  when  the  particles  are  near,  and, 
after  it  once  becomes  perceptible,  grows  immensely  with  every  addi- 
tional reduction  of  the  distance.     Half  the  distance  will  give  four 

247 


710  University  Convocation. 

times  the  force  of  attraction  ;  a  reduction  to  the  tenth  part,  will  mag- 
nify the  force  one  hundred  times  ;  and  an  approximation  which  reduces 
the  distance  to  the  hundredth  part,  will  raise  the  force  to  ten  thousand 
times  its  original  amount. 

Upon  this  law,  a  particle  brought  into  close  proximity  with  any 
small  mass  must  show  a  faint  attraction  for  it,  like  that  which  exists 
between  the  movable  particles  of  a  fluid  and  the  inner  surface  of  a 
tube  partly  immersed  in  it.  Precisely  such  is  the  force  which  we 
call  capillary  attraction.  Next,  bring  two  molecules  into  still  closer 
proximity  to  each  other,  and  the  result  must  be  a  still  more  powerful 
attraction,  corresponding  to  that  force  of  mechanical  aggregation 
which  forms  the  ordinary  masses  of  our  less  dense  minerals,  like  clay 
or  chalk.  Let  them  come  still  nearer,  into  a  proximity  measured  by 
the  minute  intervals  of  thousandths  or  ten-thousandths  of  an  inch,  and 
the  attraction  increasing  in  a  proportionate  degree  inversely,  not  as 
the  distance  but  as  the  square  of  the  distance,  must  develop  a  force 
equaling  the  highest  that  we  know — that  which  governs  the  combi- 
nations of  chemistry,  and  effects  the  cohesion  of  masses  of  homoge- 
neous matter,  like  the  pure  metallic  elements  iron,  lead,  or  gold. 

We  have  only  to  suppose  that  the  atoms  of  matter  are  determined 
by  some  such  cause  as  heat,  to  stand  at  different  distances  from  each 
other,  and  the  supposition  of  one  general  force,  varying  as  the  inverse 
square  of  the  distance,  will  give  us  as  the  inevitable  theoretical 
result,  different  manifestations  or  rather  different  degrees  of  attrac- 
tion, corresponding  to  most  of  the  well-known  forces  which  exist 
around  us.  Thus,  gravitation  will  be  but  the  attraction  of  masses 
for  each  other  at  considerable  or  great  distances ;  capillary  attrac- 
tion will  be  the  attraction  of  particles  by  some  mass  to  which  they 
are  very  nearly  approximated ;  mechanical  cohesion  will  correspond 
to  the  relation  of  particles  brought  into  much  closer  proximity — a 
force  of  far  greater  strength,  corresponding  to  the  square  of  the 
diminished  distance ;  and  the  highest  of  all  known  forces  must 
inevitably  result  from  bringing  the  atoms  of  matter  into  the  closest 
possible  approximation  to  each  other.  Our  general  theory  must 
involve  these  varied  results,  when  viewed  in  connection  with  the 
varied  distances  at  which  we  conceive  the  particles  to  stand ;  and 
the  doctrine  spreads  a  beautiful  simplicity  and  clearness  of  concep- 
tion over  the  whole  field  of  these  varied  forms  of  nature's  action. 
The  general  and  diffused  forces  of  the  universe  may  thus  be  all  con- 

248 


Natvral  Theology  of  the  Doctrine  of  the  Forces.    71 1 

ceived  as  only  varied  forms  of  gravity,  acting  under  its  single,  simple, 
and  beautiful,  law  of  the  inverse  square. 

Nor  is  there  any  reason  to  doubt  the  actual  existence  of  such  vast- 
amounts  of  force  in  these  minute  relations.  Tyndall  abundantly 
illustrates  the  immense  power  of  these  molecular  forces.  He 
describes  the  manner  in  which  an  iron  cylinder,  half  an  inch  thick,  is 
burst  with  ease  by  the  expansion  of  a  small  quantity  of  water  freez- 
ing within  it;  and  mentions  that  metallic  cylinders  of  double  that 
thickness,  are  unable  to  resist  the  force  with  which  a  small  voltaic 
battery  effects  decompositions. 

The  same  writer,  speaking  of  the  forces  involved  in  the  molecular 
changes  which  accompany  chemism,  says  : 

"  The  energy  of  the  forces  engaged  in  this  atomic  motion,  as 
measured  by  any  ordinary  mechanical  standard,  is  enormous.  I  have 
here  a  pound  of  iron  which,  on  being  heated  from  32°  to  212°  F., 
expands  by  about  -g-^o-th  of  the  volume  it  possessed  at  32°.  Its  aug- 
mentation of  volume  would  certainly  escape  the  most  acute  eye  ; 
still,  to  give  its  atoms  the  motion  corresponding  to  this  augmentation 
of  temperature,  and  to  shift  them  through  the  small  space  indicated, 
an  amount  of  heat  is  requisite  which  would  raise  about  eight  tons 
one  foot  high.  Gravity  almost  vanishes  in  comparison  with  these 
molecular  forces  ;  the  pull  of  the  earth  upon  the  pound  weight  as  a 
mass,  is  as  nothing  compared  with  the  mutual  pull  of  its  own  mole- 
cules. Water  furnishes  a  still  subtler  example."  *  *  *  "  Sup- 
pose a  pound  of  water  heated  from  3f  C.  or  39°  F.  to  4£  C,  that  is, 
one  degree  ;  its  volume  at  both  temperatures  is  the  same  ;  there  has 
been  no  separation  of  the  atomic  centers,  and  still,  though  the  vol- 
ume is  unchanged,  an  amount  of  heat  has  been  imparted  to  the  water 
sufficient,  if  mechanically  applied,  to  raise  a  weight  of  1,390  pounds 
one  foot  high."  * 

Pursuing  the  illustration,  he  estimates  the  force  employed  in  com- 
bining one  pound  of  hydrogen  with  eight  pounds  of  oxygen,  to  form' 
water,  as  "  equal  in  mechanical  value  to  the  raising  of  47,000,000 
pounds  one  foot  high."  The  substance  would  then  be  in  the  form 
of  vapor,  and,  "to  condense  this  to  a  liquid,  would  require  a  power 
equal  to  6,718,000  foot-pounds ;  and  still,  further,  to  bring  the  fluid 
water  to  the  form  of  ice,  would  require  a  force  of  993,564  foot-pounds." 

"  I  think,  "  he  observes,  "  I  did  not  overrate  matters  when  I  said 
that  the  force  of  gravity  was  almost  a  vanishing  quantity,  as  exerted 

*  See  Tyndall's  Lectures  on  Heat. 

249 


712  University  Convocation. 

near  the  earth,  in  comparison  with  these  molecular  forces."  Strangely 
enough,  Tyndall  does  not  here  recognize  these  molecular  forces  as  beino- 
themselves  but  manifestations  of  the  force  of  gravity  exerted  between 
atoms,  though  elsewhere  he  shows  that  the  conception  is  not  altogether 
an  unfamiliar  one  to  him.  But,  translating  his  statement  into  its 
more  appropriate  terms,  I  will  call  upon  you  to  observe  the  immense 
energy  with  which  gravity  unites  the  particles  when  once  they  are 
fairly  brought  within  the  scope  of  each  other's  attraction.  They  are 
held  to  each  other  with  a  power  that  we  can  hardly  estimate.  The 
force  requisite  to  unite  one  pound  of  hydrogen  with  eight  of  oxygen, 
and  condense  them  to  ice,  can  be  estimated  only  by  millions — not  less 
than  55,000,000  of  pounds  !  Most  truly  does  the  same  writer  say  on 
another  occasion,  "  The  force  with  which  bodies  expand  when  heated 
is  quite  irresistible  by  any  mechanical  appliances  that  we  can  make  use 
of.  AV  these  molecular  forces,  though  operating  in  such  minute 
spaces,  are  almost  infinite"  (mark  the  word)  "m  energy."  Here, 
again,  I  must  venture  to  put  in  a  correction.  It  is  not  "  though" 
operating,  but  because  operating  in  such  minute  spaces;  it  is  because 
the  atoms  are  brought  into  such  close  approximation,  that  the  amount 
of  force  is  so  immensely  great.  That  any  mass  of  matter,  brought 
indefinitely  near  another,  must  experience  a  vast  force  of  attraction, 
is  a  simple  consequence  of  the  law  of  the  inverse  square ;  but  as  it 
is  only  these  minute  atoms  which  can  be  so  closely  approximated  to 
each  other  as  to  feel  the  full  power  of  each  other's  attraction,  it  is 
between  them  only  that  we  find  this  extraordinary  intensity  of  force. 
The  sphere  of  their  operation  is  reduced  to  the  most  contracted  limit ; 
but  within  that  sphere  they  are  boundless.  The  atomic  forces  of 
nature  are  the  great  forces,  and,  in  precise  accordance  with  the  funda- 
mental law,  they  are  vast,  just  in  proportion  to  the  nearness  of  the 
objects  on  which  they  act ;  and  within  the  inappreciably  small  dis- 
tances of  which  we  have  spoken,  the  force  must  be  of  necessity, 
•immeasurably  great. 

This  is  the  limit  to  which  the  physical  observer  carries  his  reason- 
ings. But  the  process  cannot  stop  here.  It  is  an  accepted  doctrine  of 
our  natural  philosophy  that,  in  every  union,  chemical  or  mechanical, 
with  which  we  are  acquainted,  the  particles  still  stand  at  appreciable 
distances  from  each  other :  and  still  more  recently  it  begins  to  be 
affirmed,  as  an  indispensable  element  of  our  physical  reasonings, 
that  the  particles  of  every  solid  body  are  permanently  in  some  kind 
of  regulated   motion  or  vibration.     The  spaces  in  which  these  mole- 

250 


Natural  Theolog  y  of  the  Doctrine  of  the  Forces.     713 

cular  movements  take  place,  must  be  considerable  when  compared 
with  the  magnitudes  of  the  moving  particles  themselves.  The 
physicist  sometimes  startles  his  hearers  by  the  statement,  that  the 
immense  orbits  of  the  heavenly  bodies  are  not  more  vast  in  compari- 
son with  the  diameter  of  the  planets,  than  are  these  inter-atomic 
spaces  in  comparison  with  the  dimensions  of  the  vibrating  atoms. 
The  distances,  therefore,  which  separate  the  particles  of  a  solid,  from 
each  other,  even  in  the  closest  unions  that  we  know,  are  not  only 
appreciable,  but  must- be  regarded  as  relatively  very  great.  What, 
then,  must  follow  when  the  approximation  becomes  more  complete  — 
when  the  atoms  stand,  perhaps,  much  nearer  than  in  our  closest 
chemical  combinations  ?  Especially,  what  must  follow  when  the  dis- 
tance is  absolutely  overcome  and  annihilated,  and  the  particles  of 
matter  are  brought  into  absolute  contact  with  each  other?  Plainly, 
by  all  laws  of  reasoning,  the  force  must  in  that  event  become  infinite. 
As  the  distance  diminishes,  the  force  increases  ;  and  this  by  a  rate  more 
rapid  than  the  diminution  to  which  it  corresponds,  even  as  the 
inverse  square  of  the  diminished  distance.  Increasing,  therefore, 
by  this  advancing  rate,  the  growing  force  must  rapidly  outrun  all 
measurement ;  and  with  the  cessation  of  all  interval  between  the 
particles,  it  necessarily  surpasses  all  finite  quantity,  and  becomes 
absolutely  infinite.  The  conclusion  may  be  surprising,  even  startling  ; 
but  one  fails  to  discern  any  consideration  which  should  lead  us  to 
call  it  in  question. 

And  why  should  we  be  unwilling  to  admit  it?  Did  we  not  just 
now  hear  our  great  expounder  of  physics — Tyndall  himself — say 
that  these  forces  are  " almost  infinite?  "  But  why  "  almost  ? "  The 
limitation  is  altogether  gratuitous.  "  Not  only  almost,"  a  greater 
authority  than  he  once  said,  "not  only  almost,  but  altogether." 
If  they  are  almost  infinite  at  the  minute  distances  which  we  know, 
what  are  they,  what  must  they  be,  when  the  distances  are  annihilated, 
and  each  atom  is  given  up  to  the  full  force  of  the  attraction  which 
embraces  and  holds  it  ? 

Every  established  principle  of  reasoning — even  of  our  most  exact 
and  mathematical  reasoning — points  to  this  single  conclusion.  When 
of  two  terms  inversely  related  to  each  other,  one  wholly  disappears, 
the  other  can  be  expressed  by  no  sign  but  that  of  infinity ;  nor  can 
we  refuse  to  admit  the  result  without  impeaching  the  very  principles 
upon  which  all  reasoning  in  physics  depends. 

Such,  then,  must  be  our  general  inference  from  the  prevalence  of 

[Senate  No.  32.]  46  251       ■ 


714  '    University  Convocation. 

the  admitted  law  of  gravitation  throughout  the  universe — that  an 
infinite  force  is  exerted  in  connection  with  every  particle  of  matter. 

Of  the  objections  which  may  be  suggested  to  this  result,  I  cannot 
here  stop  to  take  particular  account.  It  is  clear,  however,  that  no 
one  of  them  can  possess  any  weight  against  our  conclusion,  which  is 
not  of  equal  validity  against  the  law  of  gravitation  itself.  It  may 
be  said  that  that  law  'is  valid  for  perceptible  distances,  but  that  we 
do  not  know  it  to  be  so  at  the  infinitesimal  distances  to  which  our 
reasoning  refers.  But  it  is  evident  that  this  is  imposing  upon  a 
known  law,  a  modification  which  has  no  ground  but  our  ignorance. 
The  atom  is  wholly  beyond  the  sphere  of  observation,  and  we  have 
no  right  to  assume,  without  some  necessity  to  dictate  the  procedure, 
that  within  the  inter-atomic  spaces,  the  law  is  at  all  different  from 
what  we  discern  it  to  be  in  those  which  are  open  to  our  observation. 

Another  objection  to  the  conclusion  which  I  have  affirmed,  arises 
from  the  belief  that  the  supposition  of  a  repulsive  force  becomes 
necessary,  to  account  for  the  continued  separation  of  particles,  which 
must  otherwise  inevitably  be  crowded  together  into  a  perfectly  com- 
pact and  dense  mass.  To  this  it  may  be  replied,  that  it  is  nut 
repulsive  force  that  causes  smoke  to  rise  from  the  earth  in  the 
atmosphere,  or  a  cork  in  water ;  neither  does  a  specific  force  of  that 
kind  need  to  be  supposed,  to  preserve  the  equilibrium  of  the 
planetary  system.  Perhaps,  therefore,  some  other  supposition  may 
be  found  adequate  for  a  similar  result  in  the  case  of  the  particles  ol 
matter.  Possibly  enough  the  established  system  of  molecular 
motions,  already  referred  to  as  existing  in  every  mass  of  matter,  as 
heat,  or  some  similar  form,  may  be  found  quite  sufficient  to  prevent 
the  apprehended  consequence  of  a  crush  of  all  material  particles 
into  a  common  center. 

I  can  only  say  that,  upon  a  somewhat  careful  consideration,  I 
have  found  no  objections  that  seem  to  be  of  any  very  decisive 
weight  agaiftst  the  conclusion  which  I  have  been  led  to  form.  For 
the  present,  therefore,  that  conclusion  must  stand  unopposed  as  the 
only  rational  result  of  accepted  scientific  principles;  and  we  are 
driven  to  admit  that  the  surest  of  our  physical  determinations — the 
law  of  the  inverse  square — implies  the  existence  of  an  infinite  force 
governing  each  particle  of  matter.* 

*  The  only  objection  which  it  seems  important  to  discuss  is  that  which  arises  from  the  idea  that 
the  force  of  attraction  between  any  two  bodies  must  be  measured  from  their  centers  of  gravity  ;  and 
that  its  maximum  cannot  be  developed  by  any  contact  of  mere  surfaces. 

252 


NA TURAL  THEOL OGY  OF  THE  D 0 CTRINE  OF  THE  FOR CES.      715 

The  next  thought  to  which  our  reasonings  conduct  us  is,  that  this 
infinite  is  one  of  a  very  high  kind.  It  is  not  the  simple  infinite  which 
would  be  furnished  by  the  law  of  a  force  increasing  inversely  as  the 
distance;  though  that,  too,  would  give  an  infinite  as  the  result  in 
every  case  of  the  actual  contact  of  particles.  But  this  is  an  infinite 
of  what  mathematicians  call  the  second  order,  involving  an  immensely 
higher  degree  of  force,  and  corresponding  to  the  geometrical  laws 
which  necessarily  govern  the  diffusion  of  any  emanation. 

It  operates,  too,  in  every  possible — nay,  in  every  conceiveable — 
direction,  from  every  particle  as  a  center;  so  that  we  have  both  an 
infinite  of  intensity,  and  an  infinite  of  direction,  involved  as  conse- 
quences of  our  original  admission  of  the  universal  prevalence  of  the 
law  of  the  inverse  square.  It  becomes  evident,  upon  consideration, 
that  this  astonishing  intensity  of  force  cannot  be  the  endowment  of 
the  atom  of  matter  with  which,  to  ordinary  view,  it  seems  to  be  con- 
nected. We  come  then  next  to  inquire,  what  is  the  seat  of  this 
infinite  force  to  which  we  have  been  brought  ?  In  what  does  so  vast 
and  amazing  a  power  inhere,  and  to  what  does  it  belong  ? 

It  is  here  to  be  observed  that  force  is  not  an  independent  and  sub- 
stantive entity  ;  it  cannot  be  conceived  as  capable  of  existing  alone. 
It  does  not  float  free  in  the  universe.  By  its  very  nature  it  exists, 
always  as  a  quality  of  some  substance.  As  motion  never  can  be 
conceived  as  real,  without  something  to  be  moved,  so  force  never  can 

This  objection  rests  on  the  demonstration  of  Newton,  that  the  sum  of  all  the  attractions  of  a 
number  of  particles  free  to  move,  is  precisely  the  same  as  if  the  whole  were  con  centrated  at  the 
center  of  a  spherical  mass.  From  this  datum  it  is  inferred  that  the  maximum  of  force  could  be 
developed  only  by  contact  of  the  centers,  and  as  these  must  forever  be  separated  by  the  sum  of  the 
two  radii,  the  absolute  maximum  never  can  be  reached. 

To  any  such  reasoning,  however,  it  may  be  replied,  that  the  center  of  gravity  is  not  an  objective 
fact,  but  only  an  abstraction  of  the  mind  itself;  it  is  a  conception  formed  for  the  simplification  of 
the  mechanical  and  astronomical  problems  which  present  themselves,  but  by  no  means  an  objective 
reality.  The  resultant  of  two  impulses  upon  a  body,  is  motion  in  an  intermediate  direction,  and  this 
may  be  treated  and  reasoned  of  precisely  as  though  the  impelling  cause  were  one.  But  the  philoso- 
pher who  should  argue  on  that  supposition  as  an  actual  fact,  might  not  be  farther  from  the  truth 
than  is  he  who  conceives  the  familiar  abstraction  of  the  center  of  gravity  to  be  the  real  point  of  the 
development  of  force. 

Moreover,  Newton's  demonstration,  on  which  the  objection  is  based,  has  reference  to  the  parti- 
cles of  a  mass  not  subjected  to  the  disturbing  influence  of  any  other  attraction.  For  matte  r  under  that 
condition,  his  conclusion  is  valid.  But  when  the  mutual  attraction  of  two  such  masses  is  in  ques- 
tion, the  conditions  of  the  problem  are  altered.  The  center  of  gravity  for  each,  is  no  longer  at  the 
absolute  center  of  the  mass,  but  approaches  that  side  on  which  the  attracting  body  exerts  its  influ- 
ence. The  conception,  therefore,  of  two  centers  of  gravity,  coincident  with  the  centers  of  the  two 
masses,  is  materially  inaccurate.  As  the  two  masses  approach  each  other,  the  two  centers  of  gravity 
may,  perhaps,  be  more  and  more  removed  toward  their  surfaces,  in  the  line  which  joins  the  centers 
of  the  two  bodies,  till,  at  the  moment  of  contact,  they  may  even  coincide  in  the  point  of  junction 
and  constitute  only  a  single  mass. 

It  seems,  therefore,  altogether  legitimate  to  say  that,  even  upon  the  supposition  of  the  reality  of 
the  center  of  gravity  as  the  point  of  maximum  energy,  the  objection  cannot  be  decisively  maintained. 

253 


716  University  Convocation. 

be  conceived  except  as  the  attribute  of  some  substance  to  which  it 
belongs  and  on  the  existence  of  which  its  own  existence  is  depend- 
ent. Force  is  evermore  the  quality  or  attribute  of  something  to 
which  it  belongs,  or  in  which  it  inheres. 

To  the  inquiry  above  suggested,  we  are  not  yet  in  a  position  to 
return  a  complete  answer.  All  that  we  can  now  say  is,  negatively, 
that  there  is  no  reason  to  think  that  such  an  astonishing  amount  of 
force  can  be  the  endowment  of  the  elementary  atom.  The  minute 
particle  cannot  possess  this  infinite  force.  It  would  violate  every 
law  of  our  thinking  to  imagine  such  a  thing.  The  atom  cannot 
be  the  infinite  ;  cannot  possess  the  infinite.  This  minimum  of  possi- 
ble existence  cannot  exert  the  maximum  of  power.  We  must  look 
elsewhere  for  its  seat.  ' 

Nor  can  we,  on  other  grounds,  admit  such  a  supposition,  since  we 
should,  in  that  case,  be  forced  to  concede  the  existence  of  many  such 
infinites.  If  each  particle  were  to  be  conceived  as  capable  of  exert- 
ing an  infinite  force,  we  must  at  once  admit  an  indefinite  number  of 
such  infinites,  a  conclusion  against  which  all  philosophy  revolts. 
There  can  be  no  such  multiplicity  of  infinites.  The  idea  is  at  war 
with  all  simplicity,  and  with  all  comprehensiveness,  of  thought. 

A  more  precise  consideration  of  this  subject  will  greatly  contribute 
to  support  the  conclusion  that  the  force  is  not  inherent  in  matter  at 
all.  Indeed,  it  is  by  no  means  in  matter  that  we  find  the  force 
which  is  the  subject  of  our  reasonings.  The  very  existence  of  the 
force  is  indicated  to  us,  not  by  anything  in  the  particle  itself,  but 
simply  by  its  motion,  by  its  change  of  position  in  reference  to  other 
particles.  Of  no  other  relation  does  the  theory  take  cognizance 
than  this  alone.  Heat  is  a  mode  of  motion,  and  heat  is  identical 
with  light,  and  identical  with  electricity,  magnetism,  etc.  All  these 
manifestations  are  referable  to  the  movements  of  atoms  in  space,  and 
gravitation  does  but  sum  up  all  these  movements  in  the  one  compre- 
hensive formula,  which  states  the  mode  in  which  this  force  varies 
with  the  varying  masses  and  distances  of  the  objects  upon  which  it 
acts.  No  one  of  these  forces  has  any  recognizable  relation  to  the 
constitution,  or  gives  us  the  least  frisight  into  the  structural  relations, 
of  the  atoms  which  they  govern.  They  relate  exclusively  to  the  move- 
ments of  these  atoms  with  reference  to  one  another.  The  fact,  the  law, 
and  the  specific  character,  of  these  changing  place-relations — these  are 
all  that  our  several  sciences  profess  to  ascertain  for  us.  In  light,  we 
have  the  measured  vibrations  which  give  us,  by  their  motion,  the 

254 


Natural  Theology  of  the  Doctrine  of  the  Forces.    7 J  7 

sense  of  color  ;  in  heat,  we  have  a  mode  of  motion,  less  rapid  and 
regular,  but  still  only  motion  ;  in  electricity  we  have  attraction  and 
repulsion  ;  in  magnetism  polarity — that  is,  motion  of  particles  and 
of  masses,  from  or  toward  the  poles  of  a  magnet ;  in  the  voltaic  cir- 
cuit, besides  the  two  last  mentioned,  we  have  the  transfer  of  particles 
from  the  positive  to  the  negative  pole,  and  chemical  combination 
and  decomposition  ;  and  in  gravitation — that  comprehensive  form 
which,  as  I  have  maintained,  sums  up  all  the  rest — we  have  only  the 
movement  of  particle  and  mass  toward  a  center.  Everywhere  we 
have  motion  simply,  mere  change  of  position  and  combination ;  and 
motion  is  always  ab  extra.  Every  motion  of  matter  that  we  know,  is 
from  some  external  source. 

E~ow,  in  all  these  forms  of  motion  there  is  no  indication  whatever  of 
anything  inherent  in  the  particle,  and  no  question  of  any  such 
thing.  The  particle  simply  changes  its  place  and  its  arrangement 
with  others.  It  is  attracted  or  repelled — combined  or  detached — 
permanently  or  transiently,  and  with  more  or  less  intensity ;  this  is 
all.  We  have  simply  the  evidence  of  a  force  which  controls  the 
movements  of  atoms  in  space — a  force  everywhere  present  through- 
out space,  and  impressing  motion  upon  the  particles  of  matter  in 
accordance  with  laws — or  more  properly,  with  a  law,  since  all  are 
one — of  great  simplicity  and  comprehensiveness. 

But  there  is  no  indication  that  this  force,  which  ever  holds  matter 
in  its  mighty  and  comprehensive  grasp,  is  resident  in  the  atoms 
which  it  controls.  All  that  we  ascertain  of  it  shows  it  rather  to  be 
pervasive,  and  universal.  It  reaches  from  atom  to  atom,  and  on, 
from  atom  to  more  distant  atom  ;  from  mass  to  mass  ;  from  planet 
to  planet ;  from  system  to  system.  It  fills  the  minute  spaces  which 
separate  atom  from  atom  ;  it  spans  the  chasm  between  orb  and  orb  ; 
it  reaches  from  system  to  system  of  the  galactic  mass,  to  which  sys- 
tems and  suns  belong — it  stretches  onward  and  outward,  and  above 
and  below — through  ether  and  media,  and  whatever  else,  till  it  fills 
the  very  immensity  of  nature,  as  the  separated  particles  of  matter 
never  do  and  never  can. 

Now,  surely,  the  force  which  is  known  to  us  solely  as  determining 
the  position  of  particles  in  space,  and  as  impressing  movement  upon 
them,  is  not  to  be  conceived  as  residing  in  the  particles  themselves. 
It  exists  no  more  truly  within  the  atoms  than  it  does  without.  It 
has  nothing  to  do  with  their  specific  constitution  or  character,  and 
does  but  impart  impulse  and  motion  to  them.     It  is  not  confined  and 

255 


718  University  Convocation, 

limited,  belonging  to  this  atom  or  to  that,  but  pertains  to  some- 
thing which  is  all-pervading,  and  which  occupies  every  void  space  in 
which  a  material  atom  exists  arid  moves. 

Why  limit  it  to  the  particle  which  it  controls  and  adjusts,  when 
it  exists  in  every  minute  void,  and  extends  throughout  every  vast 
read),  of  the  boundless  universe  to  which  our  observation  can  pene- 
trate ?  Evidently  such  a  limitation  is  needless  and  gratuitous.  The 
cosmos  is  no  chaos  of  ten  thousand  conflicting  forces,  seated  in  as 
many  separate  atoms  of  matter,  and  forming  a  combination  which  is 
but  the  resultant  of  unnumbered  oppositions  of  independent  powers. 
It  is  a  harmony,  and  it  is  one.  It  is  one,  by  virtue  of  its  great, 
simple  and  comprehensive  law,  which  is  the  harmonious  operation 
of  a  single  grand  universal  and  infinite  force,  pervading  and  control- 
ling its  every  part.  To  this  result,  the  doctrine  of  the  unity  and  the 
correlation  of  the  forces,  inevitably  conducts  us. 

And  is  it  not  thus  that  the  thoughtful  mind  has  ever  imagined  it 
to  be  i  An  Infinite  Force,  everywhere  present,  impressing  itself 
upon  every  particle  of  matter,  giving  law  to  the  universe  and  impart- 
ing motion  to  its  otherwise  dead  masses  and  forms — to  that  the 
human  mind  has  ever  been  trying  to  lift  itself — it  has  been  the 
aspiration  and  the  aim  of  every  noble  soul.  To  that  science,  after  so 
long  wandering  amid  facts,  and  phenomena,  and  laws,  now  seems 
making  its  way,  and  coming  to  support  the  aspiration  she  has  some- 
times seemed  to  suppress  and  smother. 

After  long  dealing  with  forces  and  principles  that  seemed  as 
diverse  and  conflicting  as  the  forms  and  phenomena  of  matter, 
science  gains  a  glimpse,  nay  a  conviction,  that  beneath  all  these 
varied  forms  there  is  one  general  system  of  laws,  simple  and  far- 
reaching;  and  drawing  her  breath  with  a  wonder  that  is  half  delight 
and  half  awe,  she  exclaims,  "  The  forces  of  nature  are  all  oneP 
Yes  ;  so  the  devout  mind  has  always  understood  it  to  be ;  all  forces 
in  this  vast  scheme  of  nature  are  manifestations  of  one  ;  all  life  and 
movement  have  one  great  Author. 

Pondering  yet  more  profoundly  this  great  generalization,  science 
still  further  announces  that  this  universal  force  is  a  force  inherent,  not 
in  the  particles  of  matter,  but  in  something  which  pervades  the  uni- 
verse, giving  movement  and  law  to  all  matter,  and  establishing  har- 
mony throughout  all  nature.  And  what  is  this  but  the  recognition 
of  an  immaterial  ground  and  source  of  all  the  phenomena  of  the 
world  about  us  !    One  comprehensive  and  universal  Force,  of  infinite 

256 


Natural  Theology  of  the  Doctrine  of  the  Forces.    719 

intensity,  of  unlimited  extent,  of  immaterial  nature.  Such  is  the 
issue  to  which  the  doctrines  of  the  convertibility  and  correlation  of 
the  forces  are  bringing  the  scientific  mind  of  our  day.  Shall  we 
not  accept  the  conclusion  which  does  but  translate  into  a  scientific 
formula  the  long  familiar  language  in  which  theology  has  ever  pro- 
claimed one  infinite,  omnipresent,  and  spiritual,  Lord  of  the  universe, 
and  say  with  satisfaction  and  joy,  that  surely  the  long  conflict  of 
scientific  and  religious  thought  must  be  approaching  its  end,  when 
both  acknowledge  the  universal  sway  of  the  one  infinite  force,  which 
is  at  the  same  time,  the  All  ? 

Perhaps,  however,  a  conclusion  so  gratifying  may  seem  a  little 
premature.  Is  it  quite  certain  that  the  acknowledgment  of  a  univer- 
sal force,  must  carry  with  it  the  certainty  of  so  complete  a  harmony 
of  thought  in  these  two  departments  of  reasoning  ?  Let  us  look 
somewhat  more  carefully  into  the  nature  of   our  apparent  result. 

Our  conclusion  is  that  the  agencies  of  nature  are  to  be  referred  to 
one  comprehensive  force.  But  surely  force  is  not  God.  In  order  to 
any  very  distinct  appreciation  of  that  conclusion,  we  need  to  deter- 
mine somewhat  more  accurately  what  our  conclusion  amounts  to. 

What,  then,  is  force  ? 

This  inquiry  is  one  which  physical  science,  with  all  its  effort  at  the 
accurate  measurement  and  general  identification  of  the  forces,  has 
hardly  taken  up  for  investigation.  She  has  been  content  to  rest  in  a 
vague  acceptance  of  the  conception  as  something  generally  known, 
with  little  attempt  to  ascertain  its  precise  content  of  meaning. 

One  writer  has  indeed  attempted  a  definition,  but  the  inadequacy 
of  the  result  becomes  painfully  apparent  upon  a  moment's  considera- 
tion. "  Force,"  he  declares,  "  is  motion."  As  much  motion  as  there 
is,  so  much  force  there  is,  and  no  more.  But  call  it  by  what  name 
you  will,  it  must  surely  be  admitted  that  there  is  force  where  there 
is  no  motion.  The  stones  of  an  arch  press  with  a  very  positive  and 
unmistakable  force,  upon  the  abutments ;  but  if  the  arch  is  sound 
there  is  no  motion,  and  can  be  none.  This  is  identifying  the  agent 
with  one  of  the  familiar  phenomena  by  which  it  manifests  itself,  and 
through  which  we  recognize  it ;  but  the  phenomenon  of  motion  is 
not  the  force  which  causes  the  motion.  The  meaning  of  the  word 
motion  is  abundantly  clear ;  in  its  original  and  physical  sense,  it 
denotes  simple  change  of  place  ;  and  this  is  not  what  any  man  ever 
meant  by  the  word  force.  Force  has  indeed  a  relation  to  motion  ;  it 
is  even  that  which  produces  motion ;  but  it  is   not  itself  motion. 

257 


720  University  Convocation. 

When  we  look  upon  a  handful  of  gunpowder  we  may  well  believe 
that  there  is  an  immense  force  connected  with  those  little  black 
grains  ;  but  to  say  that  there  is  any  motion  of  them,  except  by  a 
loose  metaphor,  would  be  affirming  what  our  senses  of  sight  and  feel- 
ing positively  deny. 

This  attempted  definition,  however,  is  interesting,  inasmuch 
as  it  is  the  frank  expression  of  a  great  embarrassment  in  physical 
philosophy.  Strictly,  it  is  plain  that  force  is  not  mere  motion  ; 
and  yet  it  becomes  clear,  on  reflection,  that  it  is  only  as  expressed 
by  means  of  motion,  that  physical  science  can  recognize  force 
at  all.  The  energy  —  if  it  is  more  satisfactory  to  the  scientific 
reasoner  to  describe  it  by  that  term — out  of  which  motion  arises, 
science  cannot  distinctly  recognize  as  separate  from  the  motion 
itself;  not  because  the  two  are  indistinguishable,  but  because  there 
are  no  physical  terms  for  the  description  of  the  hyper-physical  source 
from  which  motion  originates. 

So  far  is  it  from  being  true  that  force  is  conceived  as  identical  with 
motion,  it  is  not  as  motion  that,  even  in  physical  nature,  force  is 
revealed  to  us.  We  become  acquainted  with  it  not  as  motion,  but  as 
resistance  to  our  own  voluntary  effort.  When,  for  instance,  I 
attempt  to  break  a  stick,  or  to  tear  a  piece  of  paper,  I  become 
acquainted  with  the  cohesive  force  which  holds  atoms  together,  not 
by  any  motion  in  it,  or  in  them,  but  simply  by  its  resistance  to  my 
own  exercise  of  power.  The  type  of  force  is  not  motion,  but  resistance^ 
which  is  rest* — the  balance  or  equilibrium  of  forces.  So,  I  become 
acquainted  with  gravity  as  a  force,  not  by  the  observation  of  motion, 
but  by  the  resistance  which  it  offers  to  my  own  attempt  to  uphold 
an  unsupported  body. 

Indeed,  I  do  not  become  aware  of  the  force  which  I  myself  exert  in 
connection  with  my  physical  system,  through  any  observation  of  the 
motion  which  it  produces.  When  a  man,  in  walking  rapidly,  comes 
in  contact  with  some  fixed  object,  and  receives  a  blow,  or  a  shock, 
from  the  collision,  the  physiologist  tells  him  that  we  put  forth  a  great 
deal  more  force  in  our  ordinary  movements  than  we  are  at  all  aware 
of.  This  internal  exertion  of  force  becomes  so  familiar,  in  its  ordinary 
exercise,  that  we  often  do  not  notice  it;  and  the  motion  which  is  pro- 
duced by  it  fafls  entirely  to  suggest  to  the  mind  our  own  very  active 
exertion,  until  some  resistance  rudely  awakens  us  to  a  knowledge  of  the 
very  energetic  efforts  which  we  are  almost  unconsciously  putting  forth. 

*  Hesto,  or  re-mto;  not  to  move,  but  to  stand. 

258 


Natural  Theology  of  the  Doctrine  of  the  Forces.     721 

With  the  exception  of  this  one  attempt,  I  know  of  no  effort  to 
define  force  by  any  physicist;  and  this  is  simply  a  confusion  of 
motion  with  the  condition  on  which  it  depends.  The  omission  is 
so  great  that  it  naturally  suggests  inquiry.  How  is  it  that  scientists, 
so  much  concerned  with  the  subject  as  to  have  studied  very  labori- 
ously the  relations  of  each  form  of  force  to  the  others,  and  to  have 
reached  the  grand  generalization  which  unifies  all  the  specific  forces 
of  nature,  have  never  made  any  serious  effort  to  define  this  ultimate 
element  in  which  all  their  researches  terminate?  How  is  it  that 
they  have  never  felt  the  need  of  an  accurate  determination  of  the 
meaning  of  the  one  word  of  transcendent  importance,  and  of  con- 
stant occurrence,  in  all  their  inquiries?  All  the  movements  of 
nature,  we  are  told,  are  due  to  one  force ;  and  this  force  is  forever 
indestructible,  and  its  amount  forever  equal  and  undiminished  in 
the  universe;  but  when  we  ask,  "What  is  force?"  we  have  no 
answer,  and  nobody  has  ever  thought  of  the  propriety  of  framing 
an  answer,  or  has  any  answer  to  give. 

The  only  explanation  of  so  great  an  oversight,  is  to  be  found  in 
the  fact  that  the  conception  of  force  is  one  of  those  universal  ideas 
which  belong  of  necessity  to  the  intellectual  furniture  of  every 
human  mind.  It  is  one  of  those  simple  and  essential  elements  of 
our  knowledge,  which  are  imparted  to  us  by  the  very  action 
of  our  own  minds ;  and  which,  therefore,  may  well  be  assumed  as 
universally  known.  But  force  is  not  an  object  of  the  senses,  and 
no  examination. through  any  organ  of  sense,  or  through  any  instru- 
ment of  observation,  can  detect  its  presence.  It  is  not  phenomenal ; 
does  not  reveal  itself  through  any  manifestation,  but  belongs  to  the 
interior  nature  and  constitution  of  things.  Hence,  though  all 
physical  science  supposes  it,  and  all  scientific  reasonings  assert  or 
assume  its  existence,  science  can  give  no  account  of  it  by  any 
physical  characters.  It  has  no  form  or  color  for  the  eye,  and  no  sound 
for  the  ear ;  it  has  no  odor,  nor  feel,  nor  taste.  It  is  neither  solid, 
fluid,  nor  gaseous;  it  does  not  crystallize  in  any  one  of  the  six 
regular  systems  of  the  mineraldgist ;  it  does  not  combine  according 
to  any  chemical  formula ;  it  finds  no  place  in  any  latest  list  of  the 
sixty  or  seventy  known  elements.  Physical  science,  therefore,  has 
no  means  of  defining  it.  The  definition  must  be  looked  for  in  quite 
another  direction.  The  question,  what  force  is,  our  physical  philo- 
sophy has  no  means  of  answering;  and  hence  it  is  no  scandal,  nor 
reproach,  that  she  has  never  undertaken  to  answer  it.     That  deter- 

259 


722  University  Convocation. 

mination  must  come  from  a  nicer  analysis  than  either  the  qualitative, 
or  the  quantitative,  method  of  chemistry. 

All  this  is  simply  saying  that  the  conception  of  force  is  meta- 
physical, rather  than  physical,  and  is  derived  from  the  mind  and 
not  from  matter.  It  cannot,  therefore,  be  analysed  in  either  the 
wet  or  the  dry  way ;  unless,  indeed,  the  metaphysical  analysis  of 
abstract  ideas  should  be  decided  to  belong,  as  I  think  has  sometimes 
been  suggested,  to  the  latter  method. 

What,  then,  is  force,  metaphysically?  How  do  we  become  acquainted 
with  it  in  the  sphere  of  the  mind  ?  To  what  extent  is  it  known  to 
us  as  an  element  of  our  psychology  ? 

To  these  questions,  the  answer  is  not  difficult.  We  become  acquainted 
with  force  as  an  element  of  our  own  personal  experience.  We  are 
conscious  of  the  exercise  of  something  which  we  call  energy,  force,  or 
power,  in  our  own  mental  states.  Throughout  that  sphere,  we  are 
familiar  with  the  great  conception  of  action  ;  and  action  is  the  exercise 
of  force.  The  mind  is  constitutionally  endowed  with  a  power  of 
action  ;  and  this  power  of  our  spiritual  nature  is  what  we  mean  b}^  force. 
Force,  then,  is  the  active  nature  of  a  cause  ;  that  quality  by  virtue  of 
which  it  acts,  and  produces  effects.  It  is  one  of  the  elements  of  our 
very  being — an  essential  quality  of  our  intellectual  nature.  We  are 
often  conscious  of  the  exercise  of  this  activity,  and  recognize  a  power 
in  ourselves  by  which  we  are  capable  of  exertion  and  effort. 

This  exercise  of  our  activity  we  become  aware  of  in  all  the  forms 
of  perception  and  consciousness.  Thus  we  hear  some  sound,  but  are, 
unable  to  distinguish  it  clearly,  and  to  decide  upon  its  character;  and 
we  listen  with  attention,  with  an  effort,  to  discriminate  it  from  other 
sounds,  and  to  learn  its  true  nature.  So,  too,  in  vision,  we  examine 
by  the  eye  with  a  similar  strain  of  attention.  In  our  ordinary  visual 
perceptions,  the  phenomena  are  so  obvious  that  we  are  not  conscious 
of  any  effort  in  observing  them.  Hence  metaphysicians  have  often 
been  disposed  to  speak  of  the  mind  as  passive  in  its  recognition  of 
physical  objects.  But  when  the  object  is  very  minute,  or  the  charac- 
ters indistinct,  what  a  consciousness  of  effort  there  is  in  our  determina- 
tions !  The  botanist,  for  instance,  who  examines  with  his  glass  the 
obscure  organs  of  some  small  flower,  how  strenuously  does  he  exert 
his  whole  faculty  of  vision,  to  make  sure  of  the  facts  upon  which  his 
classification  depends ! 

The  same  remarkable  circumstance  occurs,  also,  in  our  purely  men- 
tal action.    What  efforts  do  we  sometimes  make  of  memory,  to  recall 

260 


Natural  Theology  of  the  Doctrine  of  the  Forces.     723 

a  lost  fact ;  of  conception,  to  grasp  a  vague  idea,  and  reduce  it  to  dis- 
tinctness ;  of  thinking,  to  trace  out  conclusions  and  consequences  !  In 
ever j  form  of  intellectual  action  we  find  frequent  occasion  to  exert 
our  power  of  knowing — that  inherent  and  universal  quality  of  our 
active  mental  being. 

Now,  in  all  these  varied  experiences  of  our  consciousness,  we 
observe  and  recognize  the  idea,  and  the  fact,  of  power  or  force.  It  is 
originally  known  to  us  as  a  quality  of  the  mind,  ever  acting,  ever 
revealing  itself  in  this  inner  sphere.  Here  we  become  acquainted 
with  force,  and  learn  to  discriminate  and  to  understand.  It  is  the  cor- 
relative of  action  ;  it  is  that  by  which  we  can  act ;  and  action  is  simply 
the  exertion  of  force.  Here,  we  know  something  about  it,  as  in 
physics  proper  we  do  not ;  and  we  distinguish  it  from  all  other  things 
by  the  clearest,  surest,  and  most  familiar,  experience. 

Now,  with 'this  knowledge  of  force,  psychologically  gained,  we  are 
able  to  understand  ourselves  when  we  speak  of  force  in  the  world 
without  us.  When  asked,  "  What  is  force  ? "  we  cannot,  indeed, 
reply  in  terms  of  physical  science,  or  physical  quality,  but,  in  the 
language  of  our  mental  experience,  we  can  give  ready  and  decisive 
answer.  It  is  the  capacity  of  acting,  the  power  of  exertion,  which 
we  ourselves  possess,  and  which  we  exercise  in  all  our  actions. 
Action,  you  will  observe,  is  our  only  word  to  describe  a  phenomenon 
of  the  mind  ;  we  can  designate  our  mental  changes  only  as  actions. 
The  word  derives  its  whole  meaning  from  our  inward  experience  in 
consciousness  ;  and  its  explanation,  when  applied  to  any  physical  fact, 
can  be  found  only  by  going  back  to  the  original  sphere  of  its  occur- 
rence, and  noting  what  it  meant  there.  All  actions  of  material 
things  have  a  meaning  derived  from  the  action  of  the  mind,  with 
which  they  are  conceived  to  be  in  some  real  analogy.  Force,  too, 
has  in  our  experience  the  same  hyper-physical  origin,  and  the  same 
intellectually  determined  signification ;  and,  apart  from  this,  the 
word  means  nothing,  and  its  use  describes  nothing.  It  denotes  a  fact 
of  deeper  meaning  than  the  mere  phenomena  of  our  observation.  It 
describes  that  profound  and  productive  energy  which  underlies  all 
the  phenomena  of  the  universe.  Force  is  the  energy  of  a  cause ;  and 
the  universal  force,  to  which  all  specific  forces  and  movements  are  to 
be  referred,  is  the  power,  ever  present,  and  everywhere  active,  of 
one  comprehensive  and  universal  Cause. 

The  bearing  of  this  conclusion  upon  natural  theology  is  immediate, 
and  important.     Every  force  is  the  quality  of  some  cause ;   but  it  is 

261 


724  University  Convocation. 

primarily  known  to  us  as  the  endowment  of  the  mind.  The  only 
cause  of  which  we  have  any  direct  and  immediate  knowledge,  is  the 
mind  itself;  the  only  force,  the  force  of  our  own  minds.  Anything, 
then,  which  becomes  known  to  us  through  the  exercise  of  force  is 
presumably  a  mind.  I  have  already  shown  that  the  forces  which 
govern  matter  are  not  the  attributes  of  the  material  particles  them- 
selves ;  they  are  one,  and  however  seemingly  different,  they  are  but 
varied  forms  of  the  force-activity  of  one  universal  Cause.  But  as  the 
only  force  known  to  us  is  the  attribute  of  an  intellectual  being, 
the  presumption  is,  that  the  comprehensive  force  of  the  universe  is 
of  the  same  kind  ;  it  is  the  attribute  of  an  intellectual  and  spiritual 
being  like  ourselves.  Such  is  the  presumption,  for  such  is  the  only 
force  the  existence  of  which  we  positively  know;  and  this  -fact 
throws  the  burden  of  proof  on  him  who  denies  the  intellectual  and 
spiritual  character  of  this  force.  It  is  contrary  to  the  analogy  of  our 
knowledge  to  suppose  the  existence  of  any  other  force  than  such  as 
we  know ;  and  whoever  does  it,  assumes  the  obligation  of  proving  the 
reality  of  what  he  assumes. 

But,  though  it  would  be  legitimate  to  do  so,  we  need  not  rest  here. 
The  advance  is  easy  to  whatever  conclusions  the  theological  hypothe- 
sis requires,  though,  under  the  limitations  to  which  such  a  paper  as 
this  is  confined,  I  can  only  indicate  very  briefly,  the  general  nature 
of  the  reasoning  which  establishes  them. 

This  universal  Cause,  then,  or  to  use  scientific  language,  the  one 
force,  is,  in  the  next  place,  creative.  It  has  shaped  and  moulded  the 
cosmical  system.  Of  creation,  in  the  sense  of  an  absolute  production 
of  matter,  science  knows  nothing.  Whence  matter  came  she  does  not 
assume  by  any  methods  of  her  own,  to  determine.  The  only  creation 
that  she  knows,  is  the  shaping  of  the  celestial  orbs,  and  the  adjust- 
ment of  their  positions  and  motions ;  and  these  are  due  to  the  one 
force  which  we  have  described  and  identified.  She  tells  us  how  in 
the  beginning  matter  existed,  "  without  form  and  void  " — a  limitless 
and  universal  mist — an  omnipresent  star-dust  throughout  space  ;  how 
gravity,  and  heat,  and  the  other  forms  of  force  began  to  condense, 
and  to  unite,  the  severed  particles,  and  to  aggregate  them  into  per- 
ceptible magnitudes  ;  how,  as  the  process  went  on,  revolving  rings  and 
spheres  were  formed  throughout  the  celestial  spaces  ;  and  how  they 
became  consolidated  into  the  rolling  orbs  of  our  visible  heavens. 
All  this  is  familiar  to  us  as  the  teaching  of  the  nebular  hypothesis; 
and  it  shows  that  the  force  of  the  universe  is  creative  and  construc- 

262 


Natural  Theology  of  the  Doctrine  of  the  Forces.     725 

tive,  and  has  given  to  the  system  of  things  its  orderly  and  beautiful 
motion,  its  profound  mathematics,  and  its  elegant  geometry. 

A  similar  method  of  reasoning  will  disclose  to  us  the  intelligence 
of  this  creative  power.  We  infer  that  the  Author  of  so  much  that 
our  intelligence  comprehends  and  delights  in,  must  be  itself  intelli- 
gent. Nor  in  this  inference,  do  we  at  all  depart  from  the  accepted 
methods  of  scientific  investigation. 

Hitherto,  and  before  the  establishment  of  the  doctrine  of  the 
convertibility  of  the  forces,  phenomena  of  each  specific  kind  had  to 
be  separately  investigated,  and  the  facts  of  each  class  to  be  organized 
into  a  separate  science.  Those  facts  could  not,  at  that  stage  of 
investigation,  be  referred  to  any  recognized  agency,  or  be  classed 
with  any  other  phenomena.  They  necessarily  formed  a  group  by 
themselves,  and  were  treated  as  the  subject-matter  of  a  distinct 
science.  Thus  electricity,  galvanism,  heat,  and  the  other  physical 
agencies,  formed  so  many  separate  departments  of  knowledge,  and 
gave  rise  to  so  many  independent  sciences.  In  each  one  of  these 
the  method  adopted  was  that  of  determining  the  character  of  the 
unknown  force,  from  that  of  the  phenomena.  These,  classified  and 
arranged,  gave  the  law  of  the  mysterious  agent  with  which  we 
were  dealing,  and  indicated  to  us  all  that  we  could  know  of  its 
nature,  and  of  its  methods  of  operation.  Thus,  in  gravity,  we  had 
the  conclusion  of  a  force,  the  law  of  which  was  that  of  the  inverse 
square ;  in  magnetism,  the  inference  was  of  a  force  acting  in  curved 
lines  from  one  pole  to  the  other  of  a  magnet.  Universally,  the 
character  of  the  unknown  agent  was  reached  by  inferences  derived 
from  the  observation  of  its  phenomena  of  force-activity. 

We  adopt  the  same  method  in  our  teleological  reasonings.  We 
study  the  phenomena  as  our  observation  discerns  them,  and  they 
indicate  the  law  of  the  unknown  force  to  be  that  of  intelligence. 
It  is  the  force  of  something  which  acts,  as  we  do,  from  a  perception 
of  reasons  and  for  the  accomplishment  of  ends.  It  has  all  the  charac- 
teristics of  an  intelligent  and  spiritual  nature,  like  that  of  the  human 
mind.* 

Did  time  permit,  it  would  be  interesting  to  proceed,  and  under 
the  same  scientific  sanction,  to  develop  yet  further  the  characteristics 

*  How  simply,  and  yet  how  forcibly,  has  Cicero  expressed  this  idea,  in  those  elegant  writings 
which  have  given  instruction  and  delight  to  the  cultivated  minds  of  every  subsequent  age  : 

"Quumque  sint  ia  nobis  consilium,  ratio,  providentia,  necesse  est  deos  hcec  ipsa  habere  majora  ; 
nee  habere  solum,  sed  etiam  his  uti,  in  maximis  et  ia  omnibus  rebus."  See  The  Be  JTalura, 
Lib.  II,  79. 

263 


726  University  Convocation. 

of  this  creative  and  general  Agent.  I  might  show  that  it  is  a  free 
and  elective  force,  acting  under  the  law,  not  of  necessity,  but  of  adap- 
tation and  choice,  and  possessing  herein  the  eminent  characteristics  of 
a  spiritual  being;  and  that  beyond  even  this,  it  is  manifested  to  us  as 
a  moral  and  benevolent  being.  It  is  a  person  ;  a  being  who  is  per- 
cipient not  only  of  mechanical  exigencies  and  contrivances,  not  only 
of  ideas  and  laws,  but  of  moral  relations,  and  of  benevolent  and 
holy  ends.  The  creative  force  of  nature  belongs  to  a  Spiritual 
Being — is  the  attribute  of  an  Infinite  God. 

Such,  then,  is  the  general  method  which  our  reasonings  must  fol- 
low ;  and  such  are  the  conclusions  which  arise  from  the  new  aspect 
of  the  physical  philosophy  of  our  day.  Surely  they  are  of  a  most 
interesting  kind.  Science  comes  to  recognize  force  as  the  basis  of 
all  life  and  motion  in  the  universe,  and  she  decides  that  the  force  is 
forever  one.  But  force  is  spiritual  and  intellectual,  and  the  neces- 
sary, or  at  least  the  probable  conclusion  is,  that  the  one  force  is  that 
of  a  spiritual  being.  Force,  however,  is  an  intellectual  conception, 
and  can  be  known  only  by  a  study  of  the  mind.  Science,  therefore, 
is  not  the  study  of  nature  alone  ;  it  embraces  as  well,  the  study  of 
man.  Science  cannot  assert  the  existence  of  force,  without  some 
knowledge  of  the  human  mind  from  which  alone  the  idea  of  force 
is  derived.  All  true  science,  therefore,  involves  both  the  knowledge 
of  nature  and  the  knowledge  of  man  ;  it  includes  the  study  of  mind, 
as  well  as  of  matter.  A  philosopher  may  pursue  either ;  but  he  can 
have  no  complete  knowledge  of  what  he  investigates,  without  bor- 
rowing from  the  other  department  of  investigation.  If  the  scientist 
would  understand  that  force  which  is  the  great  result  of  his  discov- 
eries, he  must  learn  it  in,  and  from,  the  mind,  in  which  alone  we 
discern  its  character,  and  learn  its  reality  :  if  the  metaphysician 
would  understand  the  abstractions  with  which  he  deals,  he  must 
study  them  in  connection  with  their  manifestation  in  nature.  All  true 
science  implies  a  knowledge  both  of  nature  and  of  man  ;  and  the 
knowledge  of  nature  and  the  knowledge  of  man,  together,  give  us, 
beyond  all  contradiction,  beyond  all  mistake,  the  knowledge  of  a 
universal,  infinite  force,  residing  in  an  intelligent,  moral,  and  per- 
sonal Being;  or,  in  other  words,  the  knowledge  of  God. 

264 


